[Buildroot] [PATCH v3] Makefile: respect strip exclusions for special libraries

[John Keeping]

ld-*.so and libpthread*.so* are not stripped in the same way as other
binaries because some applications need symbols in these libraries in
order to operate correctly.

However, the special handling for these binaries ignores the usual
BR2_STRIP_EXCLUDE_* rules so it is not possible to build an image which
has debugging symbols in these binaries.

Pull out the common find functionality so that we can build two find
commands that re-use the common exclusion rules.

Fix-suggested-by: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
Signed-off-by: John Keeping <john at metanate.com>
---
On Mon, 2 Jul 2018 22:25:16 +0200
Thomas Petazzoni <thomas.petazzoni at bootlin.com> wrote:

> I understand the problem, and I know you will find my comment a bit
> useless, but I find this whole thing pretty complex/noisy. Can we do
> better ?
> 
> Here is some untested initial proposal:
> 
> # When stripping, obey to BR2_STRIP_EXCLUDE_DIRS and
> # BR2_STRIP_EXCLUDE_FILES
> STRIP_FIND_COMMON_CMD = \
> 	find $(TARGET_DIR) \
> 	$(if $(call qstrip,$(BR2_STRIP_EXCLUDE_DIRS)),, \
> 		\( $(call finddirclauses,$(TARGET_DIR),$(call qstrip,$(BR2_STRIP_EXCLUDE_DIRS))) \) -prune -o ) \
> 	-not $(call findfileclauses,$(call qstrip,$(BR2_STRIP_EXCLUDE_FILES))) \) \
> 	-print0
> 
> # Regular stripping for everything, except libpthread, ld-*.so and
> # kernel modules.
> STRIP_FIND_CMD = \
> 	$(STRIP_FIND_COMMON_CMD) \
> 	-type f \( -perm /111 -o -name '*.so*' \) \
> 	-not \( $(call findfileclauses,libpthread*.so* ld-*.so* *.ko) \)
> 
> # Special stripping (only debugging symbols) for libpthread and
> ld-*.so. STRIP_FIND_SPECIAL_LIBS_CMD = \
> 	$(STRIP_FIND_COMMON_CMD) \
> 	\( -name 'ld-*.so*' -o -name 'libpthread*.so*' \)
> 
> And then:
> 
> 	$(STRIP_FIND_CMD) | xargs -0 $(STRIPCMD) 2>/dev/null || true
> 	$(STRIP_FIND_SPECIAL_LIBS_CMD) | xargs -0 $(STRIPCMD) $(STRIP_STRIP_DEBUG) || true
> 
> Thoughts ?

This looks much nicer.  I've tested it and fixed a few issues, so we end
up with this patch.


 Makefile | 44 +++++++++++++++++++++++++-------------------
 1 file changed, 25 insertions(+), 19 deletions(-)

diff --git a/Makefile b/Makefile
index 8d25c8a239..ab081412d3 100644
--- a/Makefile
+++ b/Makefile
@@ -591,20 +591,37 @@ RSYNC_VCS_EXCLUSIONS = \
 	--exclude .svn --exclude .git --exclude .hg --exclude .bzr \
 	--exclude CVS
 
-STRIP_FIND_CMD = find $(TARGET_DIR)
-ifneq (,$(call qstrip,$(BR2_STRIP_EXCLUDE_DIRS)))
-STRIP_FIND_CMD += \( $(call finddirclauses,$(TARGET_DIR),$(call qstrip,$(BR2_STRIP_EXCLUDE_DIRS))) \) -prune -o
-endif
-STRIP_FIND_CMD += -type f \( -perm /111 -o -name '*.so*' \)
-# file exclusions:
+# When stripping, obey to BR2_STRIP_EXCLUDE_DIRS and
+# BR2_STRIP_EXCLUDE_FILES
+STRIP_FIND_COMMON_CMD = \
+	find $(TARGET_DIR) \
+	$(if $(call qstrip,$(BR2_STRIP_EXCLUDE_DIRS)), \
+		\( $(call finddirclauses,$(TARGET_DIR),$(call qstrip,$(BR2_STRIP_EXCLUDE_DIRS))) \) \
+		-prune -o \
+	) \
+	$(if $(call qstrip,$(BR2_STRIP_EXCLUDE_FILES)), \
+		-not \( $(call findfileclauses,$(call qstrip,$(BR2_STRIP_EXCLUDE_FILES))) \) )
+
+# Regular stripping for everything, except libpthread, ld-*.so and
+# kernel modules:
 # - libpthread.so: a non-stripped libpthread shared library is needed for
 #   proper debugging of pthread programs using gdb.
 # - ld.so: a non-stripped dynamic linker library is needed for valgrind
 # - kernel modules (*.ko): do not function properly when stripped like normal
 #   applications and libraries. Normally kernel modules are already excluded
 #   by the executable permission check above, so the explicit exclusion is only
 #   done for kernel modules with incorrect permissions.
-STRIP_FIND_CMD += -not \( $(call findfileclauses,libpthread*.so* ld-*.so* *.ko $(call qstrip,$(BR2_STRIP_EXCLUDE_FILES))) \) -print0
+STRIP_FIND_CMD = \
+	$(STRIP_FIND_COMMON_CMD) \
+	-type f \( -perm /111 -o -name '*.so*' \) \
+	-not \( $(call findfileclauses,libpthread*.so* ld-*.so* *.ko) \) \
+	-print0
+
+# Special stripping (only debugging symbols) for libpthread and ld-*.so.
+STRIP_FIND_SPECIAL_LIBS_CMD = \
+	$(STRIP_FIND_COMMON_CMD) \
+	\( -name 'ld-*.so*' -o -name 'libpthread*.so*' \) \
+	-print0
 
 ifeq ($(BR2_ECLIPSE_REGISTER),y)
 define TOOLCHAIN_ECLIPSE_REGISTER
@@ -716,19 +733,8 @@ endif
 	rm -rf $(TARGET_DIR)/usr/share/gtk-doc
 	rmdir $(TARGET_DIR)/usr/share 2>/dev/null || true
 	$(STRIP_FIND_CMD) | xargs -0 $(STRIPCMD) 2>/dev/null || true
+	$(STRIP_FIND_SPECIAL_LIBS_CMD) | xargs -0 -r $(STRIPCMD) $(STRIP_STRIP_DEBUG) 2>/dev/null || true
 
-# See http://sourceware.org/gdb/wiki/FAQ, "GDB does not see any threads
-# besides the one in which crash occurred; or SIGTRAP kills my program when
-# I set a breakpoint"
-ifeq ($(BR2_TOOLCHAIN_HAS_THREADS),y)
-	find $(TARGET_DIR)/lib/ -type f -name 'libpthread*.so*' | \
-		xargs -r $(STRIPCMD) $(STRIP_STRIP_DEBUG)
-endif
-
-# Valgrind needs ld.so with enough information, so only strip
-# debugging symbols.
-	find $(TARGET_DIR)/lib/ -type f -name 'ld-*.so*' | \
-		xargs -r $(STRIPCMD) $(STRIP_STRIP_DEBUG)
 	test -f $(TARGET_DIR)/etc/ld.so.conf && \
 		{ echo "ERROR: we shouldn't have a /etc/ld.so.conf file"; exit 1; } || true
 	test -d $(TARGET_DIR)/etc/ld.so.conf.d && \
-- 
2.18.0